Various optical discs are being proposed. As disk-type information recording media which are detachable from recording/playback apparatuses. Such recordable optical discs are proposed as large-capacity media having a few gigabytes, and it is highly expected that they can be used as media for recording digital video (moving pictures) signals.
One of the coding methods for digital-compressing digital video signals is the MPEG (Moving Picture Experts Group) 2 method. MPEG2 is also used when recording digital video signals in information recording media. For example, when recording analog video signals in information recording media, the video signals are encoded by the MPEG2 method, and are recorded in the information recording media as an encoded bit stream. In digital TV (television) broadcasting, which has recently started, a video program encoded by the MPEG2 method is transmitted in a format referred to as a transport stream. When recording digital-broadcasting AV signals in information recording media, a transport stream is recorded as a digital signal without being decoded or re-encoded.
Video signals recorded in an information recording medium in a digital signal format can be copied into another information recording medium without the slightest loss of quality. However, this is a great problem for copyright holders of the video content.
From this point of view, for restricting copies of video signals, CCI (Copy Control Information) indicating copy generation management information, such as “Copy Free (copying can be made)”, “Copy Once (copying can be made only for one generation)”, “No More Copy (copying can no longer be made), and “Copy Prohibited (copying is not allowed)”, is added to the video signals. Such signals include, for example, CGMS (Copy Generation Management System) signals. CGMS signals for analog interfaces are referred to as “CGMS-A”, and CGMS signals for digital interfaces are referred to as “CGMS-D”. Analog CGMS-A, which is formed by superimposing ID on VBI (Vertical Blanking Interval) of video signals, is also referred to as “VBID”. The VBID is standardized as EIAJ CP-1204.
For transmitting a transport stream having CCI embedded therein, a method for encoding a descriptor having this information is known. This type of descriptor includes DTCP descriptor defined by DTLA (Digital Transmission Licensing Administrator) and digital_copy_control_descriptor defined by ARIB used in BS digital broadcasting in Japan. For further restricting copies, the embedding of copy generation management information as a watermark into a baseband video signal or an MPEG bit stream is being considered. The standardization of the watermark is currently being promoted, and the millennium format and the galaxy format have been proposed.
When recording a video signal into an information recording medium, it is required that recording restrictions be accurately imposed according to the CCI of the input signal. Generally, the user is able to record a video signal into an information recording medium only when the CCI of the input signal indicates “Copy Free (copying can be made)” or “Copy Once (copying can be made only for one generation”. When the CCI of the input signal indicates “Copy Once (copying can be made only for one generation)”, the CCI of the video signal in the information recording medium must be updated to “No More Copy (copying can no longer be made)”.
For easy understanding of the content of a video signal recorded in an information recording medium, still images, which typically represent the content, or specific scenes of the content extracted as still images are sometimes recorded separately from the video signals. These still images are referred to as thumbnail images. For example, the user selects a list of thumbnail images from the video signals recorded in the information recording medium, and displays it on a menu screen for selecting the playback start position. This makes it possible to provide a user-friendly interface. The thumbnail images may include images selected from the recorded video signals or images recorded from a personal computer or a digital still camera into the information recording medium.
Conventionally, in most cases, when predetermined video signals are copied from an information recording medium in which video signals and the corresponding thumbnail images are recorded into another information recording medium, only the video signals can be copied. In this case, however, it is more convenient for the user if the thumbnail images can be copied together with the video signals. This eliminates the need for the user to add the thumbnail images to the copied video signals later.
In this case, the management of the copyright of the thumbnail images becomes the problem. For example, many images of popular movie or television characters probably possess copyrights. Illegal copying of these images is not preferable for the copyright holders. Conventionally, however, a restriction of the copying of thumbnail images is not considered, and thus, when creating an application for copying thumbnail images together with corresponding video signals, it cannot be determined whether the thumbnail images can be copied. Thus, illegal copying of the thumbnail images cannot be prevented.